Abrasive-covered material and the like



lan. 31, 1928. l 1,657,784

G. A. BERGsTRoM ABRASIVE COVERED MATERIAL AND THE LIKE Filed Nov. 25, 1925 ATTORN EYS Patented Jim. 31, 1928.

UNITED STATES GUSTAVE A. BERGSTROM, OF RIDGEWOOD, NEW JERSEY.

ABRASIVE-COVERED MATERIAL ANI) THE LIKE.

Application led November 23, 1925. Serial No. 70,748.

My invention relates to abrasive material as exemplified for instance by the conventional emery cloth, sand paper and other devices in which abrasive grains constitute the abrading medium. In practice it has been recognized that material of this class in which the abrasive grains are arranffed as continuous abrading surfaces, quicldy deteriorate in use; for instance, such continuous abrading surfaces quickly become glazed due to the fact that the spaces between the abrasive grains become clogged up with particles of the material being abraded, whereby the grinding or polishinv' properties of vvthe abrading surface are destroyed. Attempts have been made to overcome this condition by providing the active surfaces of the material with alternate coated and uncoated portions. In an existing method this result is attained by defiecting a falling sheet of labrasive grains in a manner of strewing said grains upon a sheet in separated rows. This method is unreliable because of the fact that definite control of the falling grains is lacking and no positive precaution is provided to prevent the grains f romreaching those parts'of the sheet which are intended to remain uncoated.

The object ofY the present invention is to provide a novel and efficient method whereby an abrasive material is produced, in which the'active surface comprises alternate abrasive and non-abrading portions positively defined with respect to each other in a predetermined'manner. Other objects will appear from the description hereinafter and the features of novelty will be pointed out inthe claim.

In the accompanying drawing, whlch shows examples of the invention without defining its limits, Fig. 1 is a diagrammatic view illustrating the method /in one of lts forms and Figs. 2, 3 and 4 are face views of abrasive sheets produced in accordance with the novel method. For the purposes of illustration and description the method has been shown as applied to sheets of the class exemplified by emery cloth and sand paper. It will be understood that this 1s not intended to dene the limits of the invention and further that the novel method is capable of efficient use in connection with the production of any type of abrading material in which abrasive grains are bound together by means of a suitable binding agent.

In carrying 'out the novel method, under such conditions a coating 10 of glue or other sultable binders is applied in. a predetermined manner to a surface of the material,

illustrated in the form of a sheet 11 such as paper, cloth and the like, which thus constitutes a backing. For instance, the surface of the sheet may be completely covered with the binder 10 inv which case a coating of abrasive grains 12 is applied overall to said binder 10, while the latter is still unhardened so as to completely cover the same'. Portions of the combined adhesive 10 and grains 12 are then removed for instance, by scraping, at predetermined points to produce alternate abrasive portions a and non-abrading portions b. The aforesaid scraping operation may be accomplished for instance by means of a suitable comb 13 reciprocated in any convenient manner; in this way the binder, to `a predeterminedextent and the abrasive grains are removed simultaneously along a' plurality of parallel spaced lines. i

By properly controlling and guiding the scraping comb `13 the aforesaid lines along which the removal of the material takes place may be straight, undulating, zig-zag or otherwise to produce corresponding lines of spaced abrading strips a o n thesurfa'ce of the sheet; it will be understood that the term undulating lines as used in the claims is intended `to vcover any line other than a straight line. Thus'the scraping comb may be actuated to produce the results illustrated in Figs. 3 and 4. If desired, the removal of the material may be accomplished by two scraping combs having reciprocating movements, the paths Aof which intersect each other, and reciprocated in properly timed relation. In this way, a result such as shown by way of example in Fig. 2 is produced upon the backing sheet 11. It will of course be understood that the removal of the material takes place before the binder 10 has set or hardened.

.The results set forth labove may be also Instead of creating the binder pattern upon the materiall 11 as above described this pattern may be otherwise produced thereon; for instance, a roller or cylinder on which the pattern appears in relief may be used for applying the binder to the material 11. The abrasive grains l2 may then be applied to the binder pattern inthe same way as set forth above and produce the same results.

form alternations of abrasive and nonabrading surfaces are provided upon the material and definite channels are provided -for the exit, from the actual abrading surfaces, of the dust or particles produced by abrasion, regardless of the direction in which the abrasive coated material is used. In this way glazing of the abradi-ng surface is avoided and the life of the material as an abrasive instrumentalityis considerably in lines which may be continuous or broken and are preferably in parallel spaced relation with each other; the width of the lines of abrasive grains, the style thereof, the dimensions of the pattern and the spaces between lines of abrasive grains may vary in accordance with the purposes for which the abrasive material are to be used. In addition the difference in height between the abrasive portions and the non-abrading portions is not limited but may be varied as seems desirable. Instead of parallel lines of abrasive grains small groups thereof may be produced upon the material in predetermined patterns, the dimensions of the groups of abrasive grains and of the nonabrading portions between groups being dependent upon the use to which the abrasive material is to be put. In any case the abrasive portions or sections, whatever the character thereof may be, are clearly and sharply defined and the non-abrading sections are so arrangedv 'as to be incapable of an abrading action in the normal use of the material;

With the novel method regular and uni-4 increased. The abrasive grams are arranged,

the abrasive grains are fixed upon the material, cloth ,or other material or upon any otherl predetermined surface by means of a 'suitable adhesive or other bond. Furthermore, in all of the forms of the improvement, sand grains or other abrasive rains, either in bands or groups, lie in a eyed, mortised, or wedged relation to one another, thus creating a holdin power and adhesion of the sand or other a rasive grains to the material equal to that which 1s present in surface coated abrasives coated in the ordinary manner. This holding power is material y greater than in the case of, abrasive covered sheets or the like in which the sand or other abrasive grains are strewn over the surface; in such case the grains lie in an open arrangement relatively to each other, and are not keyed, mortised or wedged by other grains of sand. In addition to this an abrasive material produced in accordance with my improved method provides definite angles or abrasion which vary as the pattern is varied; these definite patterns may be chosen and easily produced to obtain any desired abrasive angles suitable for varying classes of work.

Various changes in the specific forms described may be made within the scope of the claim.

I claim:

The method of reducing abrasive material of the kind escribed which consists in applyin a binder to a surface of the material, app ying a covering'y of abrasive grains to said binder vcovered surface and then scraping portions of said binder and ad` hering abrasive grains from said surface simultaneously along a plurality of predetermined spaced parallel lines to roduce alternate abrasive strips and non-a fading strips on said surface.

In testimony whereof I have hereunto set my hand.

GUSTAVE A. BERGSTROM. 

